1. Field of the Invention
The present invention relates to a method of partitioning the internal space of a hollow cylindrical member, and more specifically, to a method of partitioning the internal space of a thin-walled cylindrical member by securing a thin-walled partition member in place within the cylindrical member by means of caulking.
2. Description of Related Art
A conventional method of partitioning will be described reference to FIG. 1.
A thin-walled cylindrical member 1 is formed therein with a space portion of larger diameter 2 and a space portion of smaller diameter 3. A shoulder face 5 is formed between the two portions 2 and 3. The portion of larger diameter 2 is formed at its end adjacent to the portion of smaller diameter 3 with an annular groove 4.
A partition member 17 in the form of a circular plate having a diameter substantially identical with that of the portion of larger diameter 2 is inserted into the cylindrical member 1 to rest on the shoulder face 5. A ring member 18 having an outside diameter substantially identical with the diameter of the portion of larger diameter 2 is placed on the partition member 17.
The ring member 18 is pressed against the shoulder face 5 to deform so that a portion of the ring 18 penetrates into the annular space formed between the circumferential face of the partition member 17 and that of the annular groove 4. The remaining portion of the ring member 18 is deformed on the periphery of partition member 17. In other words, the ring member 18 has to be crushed to tightly secure the partition member 17 on the shoulder face 5 and consequently to the cylindrical member 1. The internal space of the thin-walled cylindrical member 1 is thus partitioned into two chambers, the space portion of larger diameter 2 and the space portion of smaller diameter 3.
In partitioning internal space of a thin-walled cylindrical member by the conventional method as described above, a force of substantial maginitude has to be applied to the ring member and consequently to the partition member in order to tightly secure the partition member in place within the cylindrical member. In particular, if such a cylindrical member serves as a piston or cylinder which is subject to fluctuations in pressure and application of accelaration, a sufficient mechanical strength of the secured portion and a sufficient thickness of the partition member have to be insured. Accordingly, the weight of the partition member increases so that the operating speed of the piston is limited to a relatively low speed.
If greater force is applied to the ring member and partition member to provide the secured portion with greater mechanical strength, the cylindrical member, particularly the outer surface thereof, will be more deformed under the action of the force applied. In case that the cylindrical member serves as a piston which is slidably mounted within a guide member and, accordingly, high precision is required with respect to its outside diameter dimension, the outer surface of the piston has to be finished by grinding to compensate for the effect of the deformation generated during the process of securing the partition member. Such an additional grinding process causes a significant rise in the manufacturing cost.